Aladybug rests on the bottom of a tin can that is being whirled horizontally on the end of a string. since the ladybug, like the can, moves in a circle, there must be a force on it. what exerts this force?

Horizontal component of the normal force of the wall is exerting the centripetal force to the lady bug

Explanation:

Since lady bug is moving in the circle along with the tin can

So here in order to move in a circle we need a centripetal force on the object which can revolve it in a circle

This centripetal force on the tin can is due to tension force in the string

While if we consider the lady bug then it is due to the normal force of the wall of the tin can along which the lady bug is resting

so in the force diagram of Lady bug we can say

vertical component of normal force is counter balanced by the weight of the lady bug

While the horizontal component of the normal force is giving the required centripetal force to it.

there are no components of a physical goal mentioned on the list of choices that you've provided.